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Pituitary - Endocrine Axis Pathology
Pathology of the endocrine system
74
Physiology
Undergraduate 3
12/11/2013

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Term
What is seen when there is problems with the Pituitary-Thryoid axis?
Definition
Hyper and Hypothyroidism
Term
What is seen with problems in the Pituitary-Adrenal axis?
Definition
Cushing's and Addison's disease?
Term
What is seen with problems in the Pituitary-Gonadal axis
Definition
Infertility
Term
Pituitary Thyroid Axis
Definition
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Term
Hypothalamic - Pituitary - Adrenal axis
Definition
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Term
Hypothalamic - Pituitary - Gonadal axis
Definition
[image]
Term
List the anterior pituitary hormones, their regulatory hormones
Definition
• Thyroid stimulating hormone (TSH; TRH)
• Adrenocorticotrophin (ACTH; CRH)
• Luteinizing hormone (LH; GnRH)
• Follicle stimulating hormone (FSH; GnRH)
• Growth hormone (GH; GHRH & GHRIH)
• Prolactin (PRL; Dopamine)
Term
Which two ant pit hormones are under negative feedback?
Definition
GH and PRL
Term
What is different about PRL regulation, compared to regulation of the other ant pit hormones?
Definition
PRL is primarily under inhibitory control by dopamine, rather than being released upon stimulation
Term
List 5 symptoms of pituitary tumours (adenomas)?
Definition
• Headache (intracranial pressure) • Drowsiness • Seizure • Visual defects (pressure on optic chiasm) • Abnormal hormone secretion
Term
Why are adenomas considered benign, when they are associated with malignancies?
Definition
Because they are not metastatic (don;t cause cancer)
Term
What are the most common hormonal problems related to an adenoma?
Definition
1. Hyperprolactinemia
2. ACTH hypersecretion
3. GH hypersecretion
Term
(T/F) Hyperprolactinemia is the most common type of pituitary tumour
Definition
True
Term
What is seen in galactorrhea, and what sexes can have it?
Definition
- Men and women
- Spontaneous flow of milk from the tumour
Term
What is seen in amenorrhea, and what sexes can have it?
Definition
- Women only
- No period
Term
What is caused by oversecretion of ACTH?
Definition
Cushings disease
Term
What is the cause of gigantism?
Definition
Pre-pubertal GH oversecretion
Term
What is the cause of acromegaly?
Definition
Post-pubertal GH oversecretion
Term
How can a pituitary tumour destroy the gland?
Definition
- Compression compromises vascular suppl
- Disruption of the pituitary-hypothalamic axis
Term
What is the end result of this?
Definition
Hypopituitaryism
Term
(T/F) Hypopituitaryism is always caused by a pituitary tumour
Definition
False
Term
What are two other causes?
Definition
1. Sheehan's syndrome
2. Pit stalk transection
Term
What is the cause of Sheehan's syndrome, and which sex does it occur in?
Definition
Vascular collapse following an obstetrical hemmorrhage, causing death of the pituitary; women only
Term
What can cause a pit stalk transection?
Definition
- Blunt force trauma
Term
What is a unique characteristic of a pituitary stalk transection, and why does it occur?
Definition
Panhypopituitaryism, except PRL is elevated. PRL is elevated because dopamine can no longer reach the pituitary gland, and thus, PRL secretion is constant
Term
If the adenoma causes a hormone deficiency, how is it treated?
Definition
Hormone replacement of downstream hormones (no point replacing the pituitary hormones)
Term
If the adenoma causes a hormone excess, how is it treated?
Definition
1. Inhibitory drug therapy
2. Ablation therapy
Term
What is bromocryptine used for?
Definition
Treatment of hyperprolactinemia
Term
(T/F) Hypothyroidism is very rare
Definition
False, it is very common
Term
Which sex is it more common in?
Definition
Women
Term
What is the cause of primary hypothyroidism? Secondary? Which is more common
Definition
Primary (90% of cases): Thyroid gland malfunction
Secondary: Pituitary deficiency of TSH
Term
What are the 4 causes of hypothyroidism?
Definition
1. Autoimmune
2. Thyroiditis
3. Congenital
4. Surgical
Term
What is hashimotos disease?
Definition
Hypothyroidism caused by autoimmune attack on thyroid gland
Term
What are the clinical symptoms of hypothyroidism?
Definition
- Goiter
- Reduced metabolism
Term
What symptoms are seen because of the reduced metabolism?
Definition
– Pale, cool, edematous
– Cold intolerant
– Slow heart rate (bradycardia)
– Lethargic
– Decreased appetite/weight gain
Term
(T/F) Goiter is seen in both primary and secondary hypothyroidism
Definition
False, only primary
Term
Why does goiter only occur in primary hypothyroidism?
Definition
Only in primary because it is caused by overstimulation by TSH, and in secondary hypothyroidism there is reduced TSH
Term
If someone has a goiter, does this confirm that they have hypothyroidism?
Definition
No, because hyperthyroidism is also characterized by a goiter
Term
Why does lack of iodine in the diet lead to formation of a goiter?
Definition
Because no TH can be made due to the iodine deficiency, so overstimulation by TSH occurs
Term
What is the cause of cretinism?
Definition
Congenital hypothyroidism
Term
What is cretinism?
Definition
Mental retardation and growth restriction caused by untreated congenital hypothyroidism
Term
What two congenital defects can give rise to cretinism?
Definition
- Iodine deficiency
- Thryoid gland malformation
Term
What are two therapies, and do any of them have any stipulations?
Definition
- Thyroxine supplement
- Iodine replacement (only if cretinism is caused by iodine deficiency)
Term
(T/F) Neonatal screening can test for congenital hypothyroidism
Definition
True
Term
What precautions can the mother take?
Definition
Ensure adequate iodine in diet
Term
What is the most common form of hyperthyroidism?
Definition
Graves disease
Term
What is the cause of graves disease?
Definition
Autoimmune - Ab's generated that chronically stimulate TSH receptors
Term
What other 3 ways can hyperthyroidism occur?
Definition
- Thyroid nodules
- Latrogenic
- TSH secreting adenoma
Term
What is a thyroid nodule?
Definition
An adenoma that secretes TH
Term
What is the latrogenic cause of hyperthyroidism?
Definition
Overmedication of hypothyroidism
Term
What are the symptoms of hyperthyroidism?
Definition
- Goiter
- Increased metabolism
- Exophthalmus
Term
What are the signs of hyperthyroidism related to increased metabolism
Definition
- Weight loss without appetite loss
- Fatigue/muscle weakness
- Tachycardia
- Nervousness
- Heat intolerance
- Osteoperosis
Term
What is exophthalmus?
Definition
Tissue behind the eye grows and pushes the eye forward
Term
Describe what occurs in graves disease?
Definition
Constant TH production, even in the presence of a proper regulatory pathway and no TSH secretion
Term
(T/F) Graves is easily classed as primary or secondary
Definition
False, it behaves secondary (constant stimulation from an outside source), but is similar to primary because there is no problem in the feedback mechanism. However, there is no pathology of the thyroid.
Term
What 3 things are used for the treatment of hyperthyroidism?
Definition
1. Radioactive iodine
2. Medication
3. Surgery
Term
(T/F) Radioactive iodine treatment usually produces hypothyroidism, which requires thyroxine therapy
Definition
True
Term
What two medications are used in treatment of hyperthyroidism? What does each do?
Definition
1. Beta blocker - alleviates symptoms
2. Anti-thyroid drugs (propylthiouracil and methimazole)
Term
How do anti thyroid drugs work?
Definition
They interfere with thyroperoxidase, and thus prevents activation of iodine and iodination of tyrosine
Term
What is surgery used to treat?
Definition
- Cancerous thyroid nodules
- Goitre
Term
What is pheochromocytoma?
Definition
A tumour of the adrenal medulla that secretes catecholamines
Term
What are two diseases related to pathologies with the adrenal cortex?
Definition
1. Cushings
2. Addisons
Term
What is the cause of Chushings?
Definition
Excess glucocorticoids
Term
What causes the excess glucocorticoids?
Definition
- ACTH secreting tumour
- Glucocorticoid secreting adrenal tumour
- Glucocorticoid therapy of chronic inflammatory conditions
Term
What are the two types of ACTH secreting tumours?
Definition
1. Pituitary
2. Paraneoplastic (in the lung)
Term
Which of these causes is related to primary cushings? Secondary cushings?
Definition
Adrenal tumour is related to primary; all other causes are related to secondary
Term
List the clinical features of Chushings
Definition
- Obesity
- Moon face
- Buffalo hump
- Reduced muscle mass in limbs
- Stria
- Increased hair growth
Term
(T/F) The obesity cause by cushings is limited to abdominal areas
Definition
True
Term
List 4 other features of chushings
Definition
1. Osteoperosis
2. Insulin resistance
3. Delayed healing/increased infection
4. Reduced stress response
Term
Why does insulin resistance develop?
Definition
Because cortisol triggers gluconeogenic effects
Term
What is addisons disease?
Definition
A deficiency of adrenocortical hormones
Term
Which 3 hormones are missing in primary addisons? Secondary?
Definition
– Glucocorticoids (primary & secondary)
– Mineralocorticoids (primary only)
– Androgens (primary only)
Term
What are the 3 causes addisons?
Definition
- Autoimmune reaction
- Destructive tumours
- Adrenal gland infection
Term
List 6 clinical features of addisons?
Definition
• Wgt loss/Anorexia
• Weakness/fatigue
• Hypotension (salt loss)
• Hyperpigmentation
• Body hair loss
• Hypoglycemia
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